Soybean (Glycine max) is an important crop in many areas of the world, and biotechnology methods have been applied to this crop in order to produce soybean varieties with desirable traits. One such desirable trait is insect resistance. The expression of an insect resistance transgene in a plant can confer the desirable trait of insect resistance on the plant, but expression of the transgene may be influenced by many different factors including the orientation and composition of the cassettes driving expression of the individual genes transferred to the plant chromosome, the chromosomal location, and the genomic result of the transgene insertion. For example, it has been observed in plants that there is variation in the level and pattern of transgene expression among individual events that differ in the chromosomal insertion site of the transgene but are otherwise identical. There are also undesirable and/or desirable phenotypic or agronomic differences between events. Therefore, it is often necessary to produce and analyze a large number of individual plant cell transformation events in order to select an event having both the desirable trait and the optimal phenotypic and agricultural characteristics suitable for commercial success. Selecting the preferred transgenic event requires extensive molecular characterization, as well as greenhouse and field trials with many events over multiple years, in multiple locations, and under a variety of conditions. A significant amount of efficacy, phenotypic, and molecular data is collected, and the resulting data and observations are then analyzed by teams of scientists and agronomists with the goal of selecting one or more commercially suitable events. Such an event, once selected, is then used for introgression of the desirable transgenic trait into other genetic backgrounds using plant breeding methods, thus producing a number of different crop varieties that contain the desirable trait and are suitably adapted to specific local agronomic conditions.
Transgenic soybeans which rely upon expression of a single toxin for insecticidal control of insect infestation may be at risk of limited durability because of the increased likelihood of development of resistance to the toxin by the insect pests. Similarly, transgenic soybeans containing toxic agents that do not provide multiple unique modes of action could also be at risk of limited durability. The first available soybean that produces a protein toxic to lepidopterans contains a single toxin protein, Cry1Ac. A recent soybean transgenic event has been disclosed that contains Cry1Ac and Cry1F toxin proteins. If resistance to Cry1Ac occurs, the Cry1Ac and Cry1F transgenic event would be left with only the Cry1F toxin as its source of efficacy. It is therefore necessary to provide for a soybean plant that has two or more toxic agents that control the pests controlled by Cry1Ac in which none of the toxic agents bind the same or substantially the same receptors in the target insect midgut that are bound by Cry1Ac. The invention described herein provides for a transgenic soybean event MON87751 that overcomes the durability problem described above for the soybean transgenic events described in the prior art, by providing two or more agents toxic to lepidopteran pest species, in which neither toxic agent has previously been included in any soybean plant for the purpose of targeting for control the lepidopteran pests of soybean.
To make a transgenic plant containing a single transformation event, a portion of a recombinant DNA construct is transferred into the genome of a soybean cell, and the soybean cell is subsequently grown into a plant. A soybean cell into which the event is initially transferred is regenerated to produce the R0 generation. The R0 plant and progeny plants from the R0 plant can be tested for any desired trait(s), but the effectiveness of the event can be impacted by cis and/or trans factors relative to the integration site in the transformation event. The phenotype conferred by the event can also be impacted by the size and design of the DNA construct, which can vary by the combination of genetic elements in an expression cassette, number of transgenes, number of expression cassettes, and configuration of such elements and such cassettes. Identifying an event with desirable traits can be further complicated by factors such as plant developmental, diurnal, temporal, or spatial patterns of transgene expression; or by extrinsic factors, e.g., environmental plant growth conditions, water availability, nitrogen availability, heat, or stress. Thus, the ability to obtain an event conferring a desirable set of phenotypic traits is not readily predictable.